What should we do with embeddable codes in things like widgets and infographics? Should we include the rel="nofollow" by default? ...

Part of Matt's answer is

...I would recommend putting a nofollow, especially on widgets.....depending on your scale of the stuff you're doing with infographics you might consider putting a rel-nofollow on infographic links as well....

The no-follow on widgets is understandable. The no-follow on infographics is less apparent but also understandable. The reason is because the citation is not a vote for the site linked in the infographics credit.

A true citation is when a publisher gives a citation/link to your site because they think it is relevant/useful for a specific topic or product.

We discussed in 2009 [webmasterworld.com] why viral link strategies were not a long term strategy. And last year [webmasterworld.com] we discussed why infographics were not a long term strategy for much the same reasons why viral links were not viable.

Aside from build something good and tell others about it, indirect strategies also work well because they encourage actual citations.

It all may sound frustrating but if you actually target link sources that have the right amount of traffic (and most importantly the audience that is interested in your niche) it doesn't really matter that the seed links are nofollowed.

Because on the heavily-trafficked sites, people will come and read your stuff and republish it on their sites. And hopefully some of the links will not carry the nofollow attribute.

Link seeding can work really well if you find the right sites to publish your seed on.

On the other hand, if you're still trying to build the links with the pre-penguin frame of mind (or even worse if your client/boss has the pre-penguin frame of mind) please accept my condolences. Don't pull out all your hair, please!

Infographics links, in my opinion, have been flagged as unnatural. Probably should be considered a "use at your own risk" technique.

An infographic link, including so-called "link seeding" is not a vote for specific content on your site. It's republishing duplicate content with a link back to the source. Same as article directories. Infographics are an unnatural link, not a citation.

We added links in our embeds in our infographics and charts that allows users to click easily to the research where the infographics and charts were used. This is the online product of a book produced annually in collaboration with the Wall Street Journal where charts are used extensively

Given Matt Cutt's statement on this, I checked with our $125K a year SEO company if this is a risky strategy. However, we were told that with the high level authority of the site (e.g. our organization's blog is one of Technorati's top 20 politics blogs) and the fact that the link goes back to the relevant resource, that it is ok to do so.

We were told that less "authoritative" websites could suffer, but for sites with higher trust rank, that it's ok to do so.